C Specification
The VkViewport
structure is defined as:
// Provided by VK_VERSION_1_0
typedef struct VkViewport {
float x;
float y;
float width;
float height;
float minDepth;
float maxDepth;
} VkViewport;
Members
-
x
andy
are the viewport’s upper left corner (x,y). -
width
andheight
are the viewport’s width and height, respectively. -
minDepth
andmaxDepth
are the depth range for the viewport.
Description
Note
Despite their names, |
The framebuffer depth coordinate z
f may be represented using
either a fixed-point or floating-point representation.
However, a floating-point representation must be used if the depth/stencil
attachment has a floating-point depth component.
If an m-bit fixed-point representation is used, we assume that it
represents each value , where k ∈ {
0, 1, …, 2m-1 }, as k (e.g. 1.0 is represented in binary as a
string of all ones).
The viewport parameters shown in the above equations are found from these values as
-
ox =
x
+width
/ 2 -
oy =
y
+height
/ 2 -
oz =
minDepth
(or (maxDepth
+minDepth
) / 2 if VkPipelineViewportDepthClipControlCreateInfoEXT::negativeOneToOne
isVK_TRUE
) -
px =
width
-
py =
height
-
pz =
maxDepth
-minDepth
(or (maxDepth
-minDepth
) / 2 if VkPipelineViewportDepthClipControlCreateInfoEXT::negativeOneToOne
isVK_TRUE
)
If a render pass transform is enabled, the values (px,py) and (ox, oy) defining the viewport are transformed as described in render pass transform before participating in the viewport transform.
The application can specify a negative term for height
, which has the
effect of negating the y coordinate in clip space before performing the
transform.
When using a negative height
, the application should also adjust the
y
value to point to the lower left corner of the viewport instead of
the upper left corner.
Using the negative height
allows the application to avoid having to
negate the y component of the Position
output from the last
pre-rasterization shader
stage.
The width and height of the implementation-dependent maximum viewport dimensions must be greater than or equal to the width and height of the largest image which can be created and attached to a framebuffer.
The floating-point viewport bounds are represented with an implementation-dependent precision.
Document Notes
For more information, see the Vulkan Specification
This page is extracted from the Vulkan Specification. Fixes and changes should be made to the Specification, not directly.